If you really look at how the big names have gotten busted, you will see that their opsec is bad with no exceptions. Apparently people that actually know the craft don't see enough upside to running a marketplace like that, which should make you wonder about the ones that still exist.

Yes, indeed. I did look, rather carefully, a couple years ago. And OPSEC failure (sometimes spectacular) explained all of the the major busts that were widely reported.[0]

However, I did not research criminal court records. Accessing that data is nontrivial, especially for someone using a pseudonym, who can't show up physically, has no ID, and can't pay with a mainstream credit/debit card. Few, if any, courts accept Bitcoin etc.

Also, I made no effort to check for parallel construction, except by looking for inconsistencies among published accounts of investigations. And I do understand that the US DEA's Special Operations Division (SOD) funnels information from the NSA, CIA, etc to federal investigators.[1] With the understanding that "the utilization of SOD cannot be revealed or discussed in any investigative function".[2] And that includes outright perjury, if necessary. Just as we've seen regarding the use of Stinger intercepts.

It's hard to say whether people who know tradecraft well just prudently avoid running dark markets, as you say. Or whether they do, but don't get caught. Time will tell, I guess. At least, if remaining ones do get busted. But if they don't, there's the implication that the operators practice good OPSEC. Or, that they're honeypots ;)